The overall objectives of this research are to continue studies on the feasibility of, and immunologic response to interspecies storage of the heart (xenobanking), to determine if xenobanking results in privileged survival of the heart on retransplantation, and to study the role of polymorphonuclear leukocytes in rejection of skin heterografts. The specific aims are: 1) to store goat hearts for 14 to 21 days in calves and then transfer them to unrelated goats, 2) to determine the immunologic response to xenobanking in the intermediate (calf) and final (goat) hosts by immunofluorescent and cytotoxic studies and to correlate the results with histologic findings, 3) to determine if interspecies storage prolongs survival of the heart on its transfer to an untreated homologous host, and 4) to study the role of polymorphonuclear leukocytes in heterograft rejection by grafting mouse, rat, and hamster skin to skin pedicles prepared on the flank of guinea pigs.